If it was his birthday celebrations on board the special flight a couple of years ago, it was his 48th wedding anniversary fete this time on the flight from Brasilia to Havana for Prime Minister Manmohan Singh.

The normally reticent 72-year-old prime minister cut the cake with his wife Gursharan Kaur in his cabin in the company of National Security Adviser M K Narayanan and top officials on board Air India One 'Kajuraho'.

Dr Singh recalled an anecdote to enliven the occasion. The Duke of Edinburgh was once asked about marriage and he had replied that the first 25 years of marriage were normally problematic.

Kaur then butted in, "Then it is OK. We have crossed that stage (of 25 years of marriage) and there is no problem now."

Later when he came to meet the accompanying journalists, he received a round of congratulations. Of course, the prime minister was coy accepting them.

A couple of years ago, Dr Singh had celebrated his birthday on a flight between Frankfurt and New York.